Not Applicable
Not Applicable
The field of invention is vacuum pumps, and more particularly a method and apparatus for cooling the motor in a vacuum pump.
Vacuum pumps are used in many applications, for example, where a quiet, reliable vacuum is required. In many applications, the pump is a component of a larger system, so reliability of the pump is important to make the system reliable.
A prior art vacuum linear pump is Linear pump Model No. LP-200H supplied by Yasunaga Corporation, Tokyo, Japan, which is illustrated in FIGS. 1 and 2. This pump includes a vacuum pump mechanism 12 enclosed within a housing 14 that is mounted on a plenum base 16. Ducts 18 communicatively connect the pump mechanism 12 to the plenum base 16.
The housing 14, having an opening 15, encloses the pump mechanism 12 and is mounted to the plenum base 16 with screws. A gasket (not shown) interposed between the housing 14 and base 16 is required to maintain an air tight seal. The threaded opening 15 formed in the housing wall 17 is connected by a hose or pipe to supply a subatmospheric where it is desired.
The base 16 is a plenum having a port 20, a pair of passageways 22, and support legs 24. The plenum passageways 22 have upwardly extending cylindrical extensions 23 that receive the downwardly extending cylindrical ducts 18 communicatively connecting the plenum base 16 to the vacuum pump mechanism 12, forming a substantially air-tight connection.
Referring to FIGS. 1 and 2, the vacuum pump mechanism 12 has two pump assemblies 26 mounted on opposing sidewalls 28 of a hollow motor chamber 30. Each pump assembly 26 has a first chamber 32, a compression chamber 34 adjacent to the first chamber 32, and a second chamber 36 adjacent to the compression chamber 34 and disposed above and separated from the first chamber 32.
The motor chamber 30 having sidewalls 42, a top wall 50 and a bottom wall 52 encloses an electric motor 54 and is mounted to the plenum base 16 by bolting or other methods known in the art. Elastomeric isolators 56 interposed between the motor chamber 30 and plenum base 16 reduce vibrations created by the pump mechanism 12 which otherwise would resonate in the plenum base 16. Air is drawn into the motor chamber through holes 64 in the motor chamber bottom wall.
The electric motor 54 includes heat generating components, such as a motor coil 58 and laminations 60, and magnetically oscillates a shuttle 62 back and forth. The shuttle 62 actuates the flexible diaphragms 44 that form part of the common sidewalls 42 of the motor chamber 30 to vary the volume of the adjacent pump assembly compression chambers 34. Actuation of the diaphragm 44 alternately increases and decreases the compression chamber 34 volume creating an air flow from the housing opening 15 through the chambers 30, 36, 34, and 32, into the plenum base 16, and out of the plenum port 20.
As the compression chamber 34 volume increases, air is drawn into the second chamber 36 through a passageway 48 from the motor chamber 30. A one-way flapper-type inlet valve 38 fixed to the compression chamber sidewall 40 permits the air 25 to be drawn into the compression chamber 34 from the chamber 36 when the volume of the chamber 34 is expanded. A one-way flapper-type exhaust valve 46 fixed on the wall 40 permits the passage of air 25 out of the compression chamber 34 into the adjacent first chamber 32 when the volume of compression chamber 34 is reduced. The air 25 exits the chamber 32 through a duct 18 that leads into the plenum base 16.
Referring to FIGS. 1 and 2, in use, the vacuum pump mechanism 12 draws air into the housing and through the motor chamber as the motor 54 actuates the opposing diaphragms 44. Actuating the diaphragms 44 causes the respective compression chambers 34 to alternately expand and contract. Drawing the air 25 through the motor chamber 30 and into the pump mechanism 14 creates a vacuum inside the housing such that cooling of the motor is performed by air at a lower density than possible.
The present invention is a vacuum pump with an improved cooling path. Air is drawn into a plenum base disposed below a pump mechanism. Ducts supply air directly from the plenum base to the pump mechanism. The pump mechanism exhausts the air and passes it over heat generating components prior to exhausting the air into the atmosphere. Thereby, a general objective of the present invention is accomplished by providing improved cooling for the pump motor in a vacuum pump by passing relatively higher density air through the motor chamber containing the pump motor.